1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to an apparatus and a method of driving a plasma display panel.
2. Description of the Background Art
FIG. 1 is a perspective diagram of a general AC type surface discharge plasma display panel. Referring to FIG. 1, a general AC type surface discharge plasma display panel consists of front and rear substrates 122 and 124 formed of a transparent glass based material. The front substrate 122 confronting the rear substrate 124 in parallel to leave a gap of 100˜200 μm between them. In doing so, a plurality of barrier ribs 126 are provided to the rear substrate 124 by thick film printing to maintain the gap from the front substrate 122. A plurality of the barrier ribs 126 leave a distance of 400 μm from each other and a width of each of the barrier ribs 126 amounts to 50 μm.
And, a column electrode Xj (j=1, 2, , m) of an X-electrode made of Al or Al alloy is provided 100 nm thick in parallel between the barrier ribs 126 to perform an addressing function. And, an R/G/B fluorescent layer having a thickness of 10˜30 μm covers each of the X-electrodes to form a luminous layer 136.
Meanwhile, row electrodes Yi and Zi (I=1, 2, , n) of Y- and Z-electrodes are formed on a surface of the front substrate 122 confronting the rear substrate 124 to be vertical to the X-electrode. The Y- and Z-electrodes are formed about several hundreds mm by deposition of ITO, SnO, or the like to extend parallel to each other. And, the row electrodes Yi and Zi adjacent to each other form a pair to configure a row electrode pair (Yi, Zi).
Metal based bus electrodes αi and βi are formed narrower than the row electrodes Yi and Zi to adhere closely to the row electrodes Yi and Zi, respectively. The bus electrodes αi and βi are supplementary electrodes for compensating conductivity of the row electrodes Yi and Zi.
A dielectric layer 130 is formed about 20˜30 μm thick to protect the row electrodes Yi and Zi. An MgO layer 132 formed of magnesium oxide (MgO) is stacked about several hundreds nm thick on the dielectric layer 13.
After completion of forming the respective electrodes Xj, Yi, Zi, αi and βi, dielectric layer 130, and luminous layer 136, the front and rear substrates 122 and 124 are bonded to each other. After a discharge space 128 has been exhausted, a surface of the MgO layer 132 is dehydrated by baking. Subsequently, mixed inert gas including 3˜7% NeXe gas thereof is injected into the discharge space 128 at 400˜600 torr.
A unit luminous area is defined as a pixel cell P(i, j) centering around an intersection point between the electrodes Yi and Zi and the electrode Xj. In the pixel cell P(i, j), when a wall voltage is generated from addressing discharge between the electrodes Xj and Yi, sustain pulse are applied between the electrodes Yi and Zi to maintain discharge so that the fluorescent body of the luminous layer 136 can be excited to emit light. And, the light emission can be controlled by the voltage application between the electrodes Xj, Yi, and Zi via selection, maintain, and elimination of the luminous discharge of the pixel cell P(i, j).
In doing so, the sustain pulses are alternately applied to the electrode Yi and the electrode Zi, respectively. Namely, if the sustain pulse is applied to the electrode Yi, it is not applied to the electrode Zi. And, if the sustain pulse is applied to the electrode Zi, it is not applied to the electrode Yi. Thus, the surface discharge using AC can be maintained.
FIG. 2 is a circuit diagram of a general sustain pulse drive unit for supplying sustain pulses to Y-electrode and Z-electrode. And, FIG. 3 is a waveform graph of sustain pulses generated from the sustain pulse drive unit according to the related art shown in FIG. 2.
Referring to FIG. 2, a general sustain pulse drive unit includes an energy recovery circuit for being efficiently supplied with energy necessary for generating a high-voltage sustain pulse.
The general sustain pulse drive unit consists of a Y-electrode sustain pulse drive circuit and a Y-electrode sustain pulse drive circuit. And, a circuit configuration of a Y-electrode sustain pulse drive circuit 210 is identical to that of a Z-electrode sustain pulse drive circuit 220.
The general sustain pulse drive unit operates according to a 4-steps operational sequence.
First of all, in a first operational step, a first switch S1 included in the Y-electrode sustain pulse drive unit 210 is turned on, while second to fourth switches S2 to S4 are turned off. Hence, energy stored in a capacitor CS is supplied to another capacitor CP so that a sustain pulse voltage (hereinafter abbreviated VPY) applied to a Y-electrode can rise. In this case, the latter capacitor CP indicates capacitance by discharge cells of a plasma display panel.
In a second operational step, the first and second switches S1 and S2 are turned on, while the third and fourth switches S3 and S4 are turned off. Hence, the VPY maintains a sustain voltage VS.
In a third operational step, the third switch S3 is turned on, while the first, second, and fourth switches S1, S2, and S4 are turned off. Hence, the energy stored in the latter capacitor CP is discharged to the former capacitor CS to be recovered and the VPY drops.
Finally, in a fourth operational step, the third and fourth switches S3 and S4 are turned on, while the first and second switches S1 and S2 are turned of. Hence, the VPY becomes a ground level.
In accordance with the operation of the Y-electrode sustain pulse drive unit 210, the sustain pulse voltage is provided to be applied to the Y-electrode.
In order for the plasma display panel to maintain discharge, AC voltage should be applied to the Y-electrode and the Z-electrode. Hence, an operation of the Z-electrode sustain pulse drive unit 220 starts at a beginning timing point of the fourth operational step of the Y-electrode sustain pulse drive unit 210.
An operation of the Z-electrode sustain pulse drive unit 220 is as good as that of the Y-electrode sustain pulse drive unit 210. Hence, a waveform of the sustain pulse applied to the Y- or Z-electrode follows that shown in FIG. 3.
FIG. 4 is a layout of a circuit board of a drive device for a plasma display panel according to a related art. Referring to FIG. 4, a central arithmetic logical unit 410 for controlling video signal processing is located at a central part of a plasma display panel 400. A substrate 420 having a Y-electrode sustain pulse drive unit 210 formed thereon and a substrate 430 having a Z-electrode sustain pulse drive unit 220 formed thereon are provided to left and right sides of the central arithmetic logical unit 410, respectively.
And, a scan drive substrate 440 is arranged next to the substrate 420 having the Y-electrode sustain pulse drive unit 210 formed thereon. Moreover, a data drive substrate 400 for applying a data pulse to an X-electrode is arranged on the plasma display panel 400.
FIG. 5 is a waveform graph of a drive waveform outputted from a drive device of a plasma display panel according to a related art. Referring to FIG. 5, by the substrate 420 having the Y-electrode sustain drive unit 210 formed thereon, the substrate 430 having the Z-electrode sustain drive unit 220 formed thereon, and the scan drive substrate 440, a drive waveform applied to the Y- or Z-electrode is divided into a reset section for new addressing, an addressing section, and a sustain section.
And, the sustain section of the waveform in FIG. 5 is provided by the operations of the Y-electrode sustain drive unit 210 and the Z-electrode sustain drive unit 220 which were explained with reference to FIG. 2 and FIG. 3.
However, in the arrangement of the circuit board having the drive device of the plasma display panel in FIG. 4, since the sustain pulse applied to the Y-electrode is supplied to the plasma display panel via a scan IC included in the scan drive substrate 440, energy loss takes place to lower drive efficiency.
Moreover, since the substrate 420 having the Y-electrode sustain pulse drive unit 210 formed thereon and the substrate 430 having the Z-electrode sustain pulse drive unit 220 formed thereon are provided to the left and right sides of the central arithmetic logical unit 410, respectively, an overall volume of the device increases.